Improvement in ellipsographs



H. A. HAZEN. Ellipsogfaphs.

No.149,474. PatentedApril7,1874.

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UNITED STATES PATENT OE IcE.

HENRY A. HAZEN, OF NEW HAVEN, CONNECTICUT.

IMPROVEMENT IN ELLIPSOGRAPHS.

Specification forming part of Letters Patent No. 149,474., dated April7, 1874 application filed March 13, 1874.

To all whom it may concern.

Be it known that I, HENRY A. HAZEN, of New Haven, in the county of NewHaven and State of Connecticut, have invented a new Improvement inEllipsographs; and I do hereby declare the following, when taken inconnection with the accompanying drawings and the letters of referencemarked thereon, to be a full, clear, and exact description of the same,and which said drawings constitute part of this specification, andrepresent, in-

Figure 1, a perspective view, and in Fig. 2, a diagram, illustrating theuse of the instrument.

This invention relates to the construction of an instrument tofacilitate drawing ellipses, and technically known as Fellipsographfithe object being to produce an instrument so simple in its constructionand use as to be adapted to general use for the purpose of drawingellipses; and in this instrument I make use of the well-known deviceconsisting of "a cord, the two extremes of which are fixed at the twofocuses of the ellipse, the length of the cord sufficient to extend tothe extreme limits of the ellipse, and so as to guide the pencil in itsmovement; and the invention consists in a bar having one fixed eye,loop, or point, to which the cord is attached, and a second eye, loop,or point, made adjustable on the said bar relative to the first, thesaid eyes indicating the focuses of the ellipse, and the said cordadjustable as tolength, as more fully hereinafter described.

A is the bar, in which is formed a longitudinal slot, B. At one end aneye, loop, or pin, a, is fixed, preferably, in a transverse piece, 0. Dis a slide fitted to the bar, so as to be guided longitudinally andmoved freely thereon E, a

set-screw, by which the slide D may be set at any desired positionwithin the range of the slot B. On the slide D an eye, loop, or point,01, is fixed in substantially the same relative position as the eye a.

I prefer to make the parts a d as eyes simi lar to needle-eyes; but theymay be otherwise formed.

One end of a cord or thread, F, is made fast to one eye, a, and its freeend passed through the other eye, d, and the instrument is ready foruse.

Its operation is as follows: The focuses of the ellipse to be describedbeing known, set the two eyes or points a d to correspond to the saidtwo focuses; then, the extremes being known, set the pencil in the loop,as at b, the instrument lying fiat, as in Fig. 2, and draw or slaokenthe cord until the point 1) corresponds to that extreme of the ellipse;then secure the cord and run the pencil or point from the instrumentaround against the cord to the opposite point, and one-half the ellipsewill be described; then reverse the instrument and describe the otherhalf in like manner.

The instrument is preferably made of wood, is very light, cheap, simple,and'easil y adjusted, and well adapted for general use for the purposeintended.

I claim as my invention- The herein-described ellipsograph, consistingof the bar A, fixed point a, adjustable point d, and adjustable cord F,substantially as specified.

HENRY A. HAZEN.

, Witnesses:

A. J. TIBBITS, J. H. SHUMWAY.

